From 54fc3c681ded9437e4548e2501dc1136b23cfa9a Mon Sep 17 00:00:00 2001 From: Alexey Kardashevskiy Date: Tue, 31 Mar 2020 12:23:38 +1100 Subject: [PATCH] powerpc/pseries/ddw: Extend upper limit for huge DMA window for persistent memory Unlike normal memory ("memory" compatible type in the FDT), the persistent memory ("ibm,pmemory" in the FDT) can be mapped anywhere in the guest physical space and it can be used for DMA. In order to maintain 1:1 mapping via the huge DMA window, we need to know the maximum physical address at the time of the window setup. So far we've been looking at "memory" nodes but "ibm,pmemory" does not have fixed addresses and the persistent memory may be mapped afterwards. Since the persistent memory is still backed with page structs, use MAX_PHYSMEM_BITS as the upper limit. This effectively disables huge DMA window in LPAR under pHyp if persistent memory is present but this is the best we can do for the moment. Signed-off-by: Alexey Kardashevskiy Tested-by: Wen Xiong Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200331012338.23773-1-aik@ozlabs.ru --- arch/powerpc/platforms/pseries/iommu.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c index 2e0a8ea..6d47b4a 100644 --- a/arch/powerpc/platforms/pseries/iommu.c +++ b/arch/powerpc/platforms/pseries/iommu.c @@ -945,6 +945,15 @@ static phys_addr_t ddw_memory_hotplug_max(void) phys_addr_t max_addr = memory_hotplug_max(); struct device_node *memory; + /* + * The "ibm,pmemory" can appear anywhere in the address space. + * Assuming it is still backed by page structs, set the upper limit + * for the huge DMA window as MAX_PHYSMEM_BITS. + */ + if (of_find_node_by_type(NULL, "ibm,pmemory")) + return (sizeof(phys_addr_t) * 8 <= MAX_PHYSMEM_BITS) ? + (phys_addr_t) -1 : (1ULL << MAX_PHYSMEM_BITS); + for_each_node_by_type(memory, "memory") { unsigned long start, size; int n_mem_addr_cells, n_mem_size_cells, len; -- 2.7.4